((1->4)-alpha-D-glucosyl)(n) + phosphate = ((1->4)-alpha-D-glucosyl)(n-1) + alpha-D-glucose 1-phosphate

A myophosphorylase deficiency is associated with Glycogen storage disease type V, also known as "McArdle's Syndrome".A case study suggested that a deficiency in myophosphorylase may be linked with cognitive impairment.